The problem with your argument is that it's not that he blew the whistle, it's that he didn't do it in a responsible manner.
Also, whistleblowing doesn't always include breaking a law or contract. Also, he also exposed things that WEREN'T wrongdoing, and even the "wrong" things he "exposed" were pretty much already known and "wrong" is VERY subjective in this circumstance. The "wrongdoing" was not in what happened in the video, nor the number of civilian casualties, those are accidents and mistakes, but in the misrepresentation of those events. That is not really in and of itself wrong.)
And really, the thing that got him most in trouble were the hundreds of thousands of diplomatic cables that exposed no wrongdoing but still exposed state secrets.